Vector required: the case of Bursaphelenchus xylophilus and Monochamus spp. for Belgium

The pinewood nematode (PWN) Bursaphelenchus xylophilus is a quarantine nematode which is currently absent in Belgium. Its status is based on phytosanitary controls of imported wood products and annual national surveys by the Belgian Federal Agency for the Safety of the Food Chain (FASFC). These measures have been implemented since 2000 following the first report of the PWN in southern Europe in 1999. It is unclear if and how the PWN will spread and/or establish throughout Belgium if it is introduced in the future, as there is no knowledge concerning the presence of its vectors, longhorn beetles of the genus Monochamus. It is essential to identify Monochamus species occurring in Belgium and map their geographic distribution and densities in order to develop an eradication strategy for possible PWN contaminations. We are gathering this information by stimulating public participation in the search for these longhorn beetles and by surveying the Belgian pine forests using a network of attractant traps. During the first two years of our 3-year project only a few adults of M. galloprovincialis and M. sartor were found at 6 locations in Flanders, and none in the Wallonia and Brussels regions. To increase the efficiency of the monitoring system, trap-attractant combinations were evaluated and the application of ‘wet catching’ was examined. Cross-vane traps containing 2-undecyloxy-1-ethanol (monochamol), ipsenol, 2-methyl-3-buten-1-ol and alpha-pinene resulted in higher catches of longhorns than intercept traps excluding alpha-pinene. The effect of monoethylene glycol (MEG), a preservative used in wet catching, on the diagnostic features of PWN was evaluated. While morphological features deteriorated with increasing concentrations of MEG and with time, molecular detection of the nematodes was not affected. Further experiments and field monitoring during the final year of the project (2015) should indicate if the observed longhorn individuals are endemic or imported. The information gathered will result in designing a monitoring program based on risks of PWN spread linked to the density of the vector population and action programs for Belgium.